Nokia 5110 LCD text appears faded with back light on.

Other Hardware General Electronics
1

Hi,

I have a Nokia 5110 LCD that I have been using as a display for my project with Arduino Uno. The display has been working fine all along at 3.3 V. I recently ported the project to an Atmega328P on another breakout board that had only 5V Vcc. The LCD worked fine on this new board as well. All along, I had never used the back light on the LCD. Yesterday, I decided to give it a try and connected the back light pin and turned it to high on my old arduino board at 3.3V. Now, with the back light on, the display works, but the text appears faded.

I later set the back light pin to low, uploaded the code on to the Uno and ran the application. But, even with the back light off, the text still appears faded.

Is the display broken? Has anyone faced similar issues, and have been able to address it successfully?
Kindly suggest.

Thanks,
Raajesh

2

Probably typical. These devices can change behaviour simply by pressing on the sides of them etc. I ordered a whole bunch of these things. The quality/appearance of the text can vary between individual modules. That's what I've noticed.

3

The 5110 displays are re-cycled and cheap, so its no surprise some of them are dodgy.

4

raajesh:
Is the display broken? Has anyone faced similar issues, and have been able to address it successfully?
Kindly suggest.

Could be broken.

Check how much the supply voltage drops to the display when the backlight is turned on and report back.

5

Hi,

Thanks for your reply, srnet and Southpark.

I just got home after work and tried the same exercise (without the backlight of the LCD on) and it works fine. Not sure what changed. Perhaps the board had a loose contact. I guess, I will let it be, and see if it stays that way.

6

These displays are mostly salvaged from old Nokia phones sold in many millions due years. It condition is questionable as they are reused from old phones, however if they work correctly, it will work correctly for a long time.

I have bought long time ago one display board from Sparkfun and almost returned when I tested arduino code from their site - apparently nothing displayed. However, after looking from other angles I have saw something. It was necessary only to set different contrast. That is the same problem from another view.

From your description, over-voltage may cause temporary or permanent damage. These displays are 3.3V power rated and 3.3V SPI lines tolerant. Anyway, on some cheap Chinese display board clones may wrote they are 5V tolerant, which may be fatal as that may be absolute max limit. In these conditions device lifetime may be radically shorten.

If use with 5V device, I suggest to use 3.3V regulator and 4050 for SPI lines, it will last much longer.